A new amorphous heat‐resistant aromatic polymide fiber prepared by wet‐spinning

Abstract

AbstractA new amorphous heat‐resistant aromatic polyamide was prepared by solution polymer‐ization in N‐methylpyrrolidone, (NMP) from equimolar amounts of 4,4′‐methylenedianiline, p‐phenylenediamine, isophthaloyl chloride, and terephthaloyl chloride. After neutralization of the byproduct HCl, with calcium hydroxide, the as‐polymerized polymer solution (15.7% polyamide in NMP) was spun directly on a horizontal wet‐spinning device. Yarn drawing of as‐spun fibers, near the glass transition temperature of the polymer, was performed on a hot‐drawing equipment. To determine the optimal drawing conditions, the influence of the draw ratio on the tensile properties was studied in detail. On the basis of these results, a draw ratio of 1.7 was applied to prepare a larger quantity of drawn polyamide multifilament yarn (f330 and f500). Tensile properties of both fibers and filaments were determined by standard methods. The fibers are characterized by an excellent thermal stability as indicated by temperature‐dependent tensile measurements, long‐term heat resistance, boiling‐water shrinkage, hot‐air shrinkage, etc., of the fibers. Despite the amorphous character of the polyamide fiber, it offers an excellent resistance to common organic solvents (except to THF and DMF). Moreover, the fiber exhibits a good resistance toward diluted inorganic acids, salts, and bases. Depending on the specific properties of the polyamide fiber, the material may find applications in, e. g., hot‐air filter fabrics, protective clothing, electrical insulation paper, or advanced structural materials. © 1993 John Wiley & Sons, Inc.